Age-specific variation in reproduction is largely explained by the timing of territory establishment in the New Zealand stitchbird Notiomystis cincta

1. Using data from 327 nests over a consecutive 8-year period we examined age-specific variation in reproduction in a population of stitchbirds (or hihi) Notiomystis cincta and related how differences in reproductive performance were linked to the timing of territory establishment and breeding. 2. Across the population all reproductive parameters showed a quadratic relationship with an increase mainly between the first and second breeding season and a decline after the fourth year. A longitudinal analysis showed evidence of senescence by the sixth year in the numbers of chicks fledged and recruited. 3. Reproductive increases between years 1 and 2 were the result of poor-quality females dying after their first breeding season (differential selection hypothesis) in combination with surviving females showing improvements in reproduction in their second year (individual improvement/constraint hypothesis). 4. There was no effect of mate experience or territory quality on improvements in breeding between years. 5. The key variable influencing reproductive output was the timing of breeding. Birds that started laying earlier were more likely to lay multiple clutches in any given season. This was the main difference between first-year and older birds; generally first-year birds initiated egg laying later and consequently laid fewer clutches. 6. Approximately half of all first-year birds did not establish their territory until after the breeding season had begun. This delay in territory establishment resulted in these birds delaying breeding, which resulted in them having a lower reproductive output relative to all other birds. First-year birds that managed to establish their territory before breeding commenced, had similar rates of reproduction as older birds. 7. There was a positive relationship between the timing of territory establishment during a female's first year and her hatching date in the previous breeding season. We hypothesize that this was because late-hatched females were less able to effectively compete for territories against earlier-hatched members of their cohort, and this delayed their establishment and breeding in their first year. Thus, this social constraint is likely to be a major factor driving age-specific reproductive variation in this population.     

Carotenoids, colour and conservation in an endangered passerine, the hihi or stitchbird (Notiomystis cincta)

Carotenoids are essential dietary components utilized not only in pigmentation but also as immuno-stimulants and antioxidants. Reduced availability can have consequences on individual health and survival, thus making carotenoids a good indicator of environmental stress. We compared carotenoid profiles and plumage colour characteristics of an endangered passerine species in New Zealand, between its remnant island source population and two reintroduced island populations. Circulating carotenoids were predominantly lutein (mean of 82.2%) and zeaxanthin (mean of 14.8%), and these were the major carotenoids present as yellow pigments in the males' plumage. There were clear differences in total carotenoid concentrations and plumage colour among the three populations. Circulating carotenoid concentration was significantly higher in one of the reintroduced populations, and the yellow plumage of males was significantly higher in both reintroduced populations in comparison with the remnant population (reflected as a significant increase in hue). Understanding how these differences arise may be of importance to this species given the health benefits carotenoids impart and our ability to select plant species containing these compounds or artificially supplement them.     

Aspergillosis and other causes of mortality in the stitchbird in New Zealand.

Necropsy findings from natural deaths in free living and captive stitchbirds (Notiomystis cincta) were examined over a 3 yr period (November 1991-94) to establish whether disease was an important factor in translocation failures and captive breeding programs undertaken by the New Zealand Department of Conservation. Fresh and fixed material from seven free-living birds and 11 captive birds were examined and were compared with those of a retrospective study of archival material from captive and wild birds collected over a 13 yr period (1979-91). The causes of death in both the present and retrospective study showed a similar pattern with aspergillosis and aspiration pneumonia being the most significant cause of mortality in captive birds. Aspergillosis was diagnosed as the cause of death in 11 of 31 stitchbirds from Mt Bruce; eight of these deaths occurred in the winter months (June-August). The other causes of death in captive birds included trauma, coccidiosis, and sporadic bacterial infections. Hemosiderosis and airsacculitis were common histological findings in most of the wild and captive stitchbirds examined.     

Female mate preferences and subsequent resistance to copulation in the mallard

In the majority of socially monogamous bird species, femalessolicit or accept copulations from males other than their partner.Females may gain direct benefits from extrapair males, suchas greater access to resources, or indirect genetic benefitsthat will influence the future success of their offspring. However,one group of birds appears to be the exception to this generalrule; in the wildfowl (Anseriformes), all extrapair copulationsappear to be resisted by females. It has been suggested thatresistance behavior may be a strategy to allow females a greaterchoice of mates, either at the precopulatory level (to promotechoice of copulation partner) and/or the postcopulatory level(to promote multiple mating to increase their choice of sperm).This paper examines the function of female resistance behaviorin one of the dabbling ducks, the mallard (Anas platyrhynchos).Observations on a marked population of wild mallard and experimentswith captive birds found that although females showed a strongpreference for particular males that are the first to molt intotheir breeding plumage, male attractiveness did not influencefemale responses to pair or extrapair copulation attempts. Femaleresistance decreased the likelihood that copulation attemptswould end in successful insemination. The findings did not supportthe hypothesis that females resist copulations to promote femalechoice and the reasons why waterfowl may benefit from avoidingall extrapair copulations are discussed.     

Male provisioning is negatively correlated with attempted extrapair copulation frequency in the stitchbird (or hihi)

In species with biparental care of offspring and high levels of extrapair parentage, paired males may suffer reduced fitness by investing in offspring that are not their own. In such instances, males are predicted to evolve some form of discrimination between kin and nonkin and vary investment accordingly. One simple form of discrimination is to follow behavioural cues to paternity. We investigated paternal contribution to chick rearing in a socially monogamous population of stitchbirds, Notiomystis cincta, with high levels of extrapair copulation (EPC) and extrapair paternity. The relative contribution of the male to chick provisioning was negatively correlated with attempted EPC frequency. Because the majority of EPC attempts are forced and conspicuous in stitchbirds they are an obvious cue for males to use. Copyright 2000 The Association for the Study of Animal Behaviour.     

Condition dependence of nestling mouth colour and the effect of supplementing carotenoids on parental behaviour in the hihi (Notiomystis cincta)

Carotenoids are integument pigments that often reflect foraging efficiency, disease resistance and body condition. In contrast to the widespread attention this relationship has received in adult birds, the condition dependence of nestling colouration remains an understudied component of animal communication. Here we assess the condition dependence of carotenoid pigmentation in nestling hihi (Notiomystis cincta, an endangered New Zealand bird) and examine the influence of carotenoid supplementation on nestling quality and parental visitation rates. Our results show that carotenoids provided to breeding adult hihi were transferred to their offspring and resulted in an intensified orange-yellow flange colour. After accounting for carotenoid supplementation the parameter that most consistently explained variation in nestling flange colour was nestling tarsus length at 23 days, indicating condition dependence of this trait. We did not, however, detect direct effects of carotenoid supplementation on nestling mass or immune response (or any other fitness parameter measured). Carotenoid supplementation did, however, result in an increased paternal provisioning rate.     

New loci from New Zealand Black and New Zealand White mice on chromosomes 4 and 12 contribute to lupus-like disease in the context of BALB/c

New Zealand Black (NZB) and New Zealand White (NZW) mice are genetically predisposed to a lupus-like autoimmune syndrome. To further define the loci linked to disease traits in NZB and NZW mice in the context of the BALB/c genetic background, linkage analyses were conducted in two crosses: (NZW x BALB/c.H2(z))F(1) x NZB and (NZB x BALB/c)F(2). Novel loci linked to autoantibody production and glomerulonephritis, present in both NZB and NZW mice, were identified on proximal chromosomes 12 and 4. The chromosome 12 locus showed the strongest linkage to anti-nuclear Ab production. Additionally, a number of other novel loci linked to lupus traits derived from both the New Zealand and non-autoimmune BALB/c genomes were identified. Furthermore, we confirm the linkage of disease to a number of previously described lupus-associated loci, demonstrating that they are relatively background independent. These data provide a number of additional candidate gene regions in murine lupus, and highlight the powerful effect the non-autoimmune background strain has in influencing the genetic loci linked to disease.     

Prolonged or repeated copulation and male longevity in the tick Ixodes rubicundus

Male Ixodes rubicundus were found in copula with attached females in 59% of individuals. The number of males attaching to the female integument or to the the host negligible. In laboratory experiments, males enclosed with females in a small vial had significantly longer life spans than solitary males. Paired males were found to be in copula on 20-34% of observations. Solitary males lost weight while paired males gained weight over a 2-day period. However, the specific energy content of the 2 groups remained constant.     

Reproductive patterns in mantled howler monkeys: Estrus,mate choice and copulation

The present study was undertaken to evaluate non-random mating patterns in two groups of mantled howler monkeys in two tropical dry forest habitats. Sexual dimorphism, female estrus stage, male dominance rank, sexual solicitations and copulations were assessed. Males are significantly larger than females, but female weight varies more than male weight. The length of female estrus cycles is comparable in both habitats, but females in the more strongly seasonal habitat demonstrate greater estrus synchrony relative to their numbers. Males solicit potential mates more frequently than females, a pattern explained by the relatively high rate of sexual solicitation by high-ranking males. Females in “peak” estrus solicit “alpha” males, while females in other stages of estrus solicit males equally by rank. Intersexual aggression occurs rarely, and “forced copulations” are attempted but, apparently, are unsuccessful. Sexual solicitations by “alpha” males and “peak” estrus females are most likely to lead to copulation, and “alpha” males are more likely to copulate than “gamma” males. In general, latencies from first solicitation to copulation are expensive in time, especially for high-ranking males. Estimated annual reproduction success favors high-ranking males, and results indicate that male and female mating behavior is mutually coordinated and controlled.     

Sexual exhaustion in White New Zealand male rabbits of different ages

Sexual exhaustion was studied in hybrid White New Zealand rabbits of different ages, for this purpose six young rabbits from 6 to 12 months of age, and six adult rabbits of 14-20 months of age were selected. Sexually receptive females were taken to the male's cage, for a period of 4 min, if copulation was not performed, the observation was then considered finished. If the male mounted within this period of time, the mounted female was immediately replaced by another female and 4 min of exposure time to the male were reinitiated, and repetitions were conducted until the male that was being studied refused to mount a new female at which time the male was considered to be sexually exhausted. Young rabbits mounted and ejaculated 9-10 times before sexual exhaustion. Adult rabbits showed a fluctuation of between 6 and 8 mounts per ejaculations before refusing another mount. The statistical analysis with a Mann-Whitney U-test, showed that the Rank sum for group A was 57, while for group B was 21. The U-value was 0.0 and the adjusted Z -2.9943. A significant difference was observed between groups with a value of P=0.00275. In the present study it was demonstrated that there is an influence of age on sexual behavior of rabbits.     

Androgen regulation of the motor copulatory pattern in the male New Zealand white rabbit

The effect of castration and testosterone propionate (TP) treatment on the motor copulatory pattern was studied by an accelerometric technique in five sexually experienced New Zealand white male rabbits. This technique permits the oscillographic recording of thrusting frequency, rhythmicity, and amplitude of the pelvic movements occurring during copulation. Castration resulted in a marked decrease in sexual activity in all rabbits. Mounting, including occasional intromissions, was retained by four of the rabbits for periods ranging from 2 to 15 weeks. Castration did not affect mount duration, but decreased strength and frequency of pelvic thrusting. Diminution in the frequency of pelvic thrusting was mainly due to intercalation of pauses within the mounting trains. The change in the rhythm of pelvic thrusting was related to the failure of most mounts performed by castrated rabbits to stimulate lordosis in the female. Testosterone propionate (TP, 10 mg daily for 15 days) restored mounting activity and increased strength and frequency of pelvic thrusting in all rabbits. It is concluded that TP, besides stimulating sexual motivation, regulates the vigor and rhythm of pelvic movements during copulation in the rabbit.     

The lifetime costs of increased male reproductive effort: courtship,copulation and the Coolidge effect

The reproductive effort that a male directs to a familiar female declines over time, suggesting decreasing marginal returns. But is this diminishing returns a function of increasing reproductive costs or decreasing benefits of sustained effort? Here, we use the restoration of male reproductive effort with unfamiliar females to differentiate the role of diminishing returns and lifetime costs of increased reproductive effort of male guppies. We kept males with familiar or unfamiliar females throughout their lives and manipulated their ability to either court or mate with females. We found that increased male reproductive effort with novel mates lead to an immediate trade‐off in the form of reduced foraging effort. Further, males able to mate with a series of unfamiliar females had lower lifetime growth, indicating the primary cost of male reproductive effort in guppies arises from copulation rather than courtship. The lifetime growth trade‐offs were significant only when males mated with unfamiliar mates, suggesting that male reproductive effort with familiar females declines before it is restricted by physical exhaustion. These findings provide some of the first evidence of longitudinal costs of increased male reproductive effort in a vertebrate.